Perez Velazquez J L, Frantseva M V, Carlen P L
Playfair Neuroscience Unit, Toronto Hospital Research Institute, Toronto, Ontario M5T 2S8, Canada.
J Neurosci. 1997 Dec 1;17(23):9085-94. doi: 10.1523/JNEUROSCI.17-23-09085.1997.
Ischemia-induced cell damage studies have revealed a complex mechanism that is thought to involve glutamate excitotoxicity, intracellular calcium increase, and free radical production. We provide direct evidence that free radical generation occurs in rat CA1 pyramidal neurons of organotypic slices subjected to a hypoxic-hypoglycemic insult. The production of free radicals is temporally correlated with intracellular calcium elevation, as measured by injection of fluo-3 in individual pyramidal cells, using patch electrodes. Free radical production (measured as changes in the fluorescence emission of dihydrorhodamine 123) peaked during reoxygenation and paralleled rising intracellular calcium. Electrophysiological whole-cell recordings revealed membrane potential depolarization and decreased input resistance during the ischemic insult. Glutamate receptor blockade resulted in decreased free radical production and markedly diminished intracellular calcium accumulation, and prevented neuronal depolarization and input resistance decrease during the ischemic episode. These results provide evidence for a direct involvement of glutamate in oxidative damage resulting from ischemic episodes.
缺血诱导的细胞损伤研究揭示了一种复杂机制，该机制被认为涉及谷氨酸兴奋性毒性、细胞内钙增加和自由基产生。我们提供了直接证据，表明在遭受缺氧-低血糖损伤的器官型脑片的大鼠CA1锥体神经元中会产生自由基。通过使用膜片电极向单个锥体细胞注射荧光素-3测量，自由基的产生在时间上与细胞内钙升高相关。自由基产生（以二氢罗丹明123荧光发射的变化来衡量）在复氧期间达到峰值，并与细胞内钙升高平行。电生理全细胞记录显示，在缺血损伤期间膜电位去极化且输入电阻降低。谷氨酸受体阻断导致自由基产生减少，细胞内钙积累明显减少，并防止了缺血发作期间神经元去极化和输入电阻降低。这些结果为谷氨酸直接参与缺血发作导致的氧化损伤提供了证据。
